A prior art method of producing particles of iron carbide (Fe.sub.3 C) by feeding particles of hematite (Fe.sub.2 O.sub.3) into a fluidized bed reactor, while fluidizing said particles by a reaction gas, is disclosed, for example, in Publications of the Translation of International Patent Application No.6-501983 (PCT/US91/05198). In this prior art, preheated particles of iron ore are fed into a fluidized bed reactor and carburized by a reaction gas containing carbon monoxide (CO), or the like, to produce particles of iron carbide, such as cementite (Fe.sub.3 C). An efficient conversion of iron ore containing a high iron oxide content, such as hematite, into iron carbide would become a major technique for extracting iron from iron ore because iron carbide can be used directly as a source of iron in steel making furnaces, such as electric furnaces.
FIG. 6 illustrates the change of the reaction composition with increasing reaction time as shown in the FIG. 8 of Publications of the Translation of the International Patent Application No.6-501983. The iron oxide fed at the time 0, which contains about 60 percent of Fe.sub.3 O.sub.4 and about 40 percent of Fe.sub.2 O.sub.3, is converted into iron carbide (Fe.sub.3 C). However, the production rate of iron carbide is remarkably slower in the latter part of the reaction (i.e., after 4 to 6 hours). It is recognized that a longer reaction time would be required to reduce iron oxide, such as Fe.sub.3 O.sub.4 and FeO, and obtain iron carbide (Fe.sub.3 C) at a high conversion ratio. In a fluidized bed reactor, a long passage, i.e., flow path, is required in order to achieve a long residence time of particles in the reactor, and the section area of the flow path has to be increased to obtain a large quantity of iron carbide. Accordingly, a large-scale fluidized bed reactor must be installed in order to obtain a large quantity of iron carbide at a high conversion ratio.
The present invention is intended to increase the production rate of iron carbide in the latter part of the reaction, and thereby provide a process for efficiently producing iron carbide and an equipment therefor without increasing the size of the fluidized bed reactor.